1. Field of the Invention
The field of the invention relates to trigger sprayers of the type wherein structure is provided for preventing pressurized liquid from being expelled from an outlet orifice in a nozzle of a trigger sprayer until a predetermined pressure of the liquid is reached in a pumping cylinder and the ejection of liquid in a SPRAY, a STREAM or a FOAM is stopped or cut off when the pressure of the liquid being pumped by the trigger sprayer in the pumping cylinder falls below a predetermined pressure.
More specifically, the invention relates to a precompression valve in a pumping cylinder of a trigger sprayer which only allows pressurized liquid to be expelled when the pressure of the liquid in the pumping cylinder is above a certain predetermined level.
2. Description of the Related Art Including Information disclosed under 37 C.F.R. 21211,97-1.99
Heretofore various trigger sprayer arrangements have been proposed for ejecting, expelling or dispensing liquid under pressure from a liquid dispenser only when the liquid being dispensed is at a predetermined pressure.
Also, structure has been proposed for minimizing the volume of the passageway through which the liquid to be ejected travels before it is ejected from an outlet orifice of the sprayer.
Examples of previously proposed liquid dispensing structures, including trigger sprayers and non-analogous pump type sprayers, for maintaining the liquid being expelled in a STREAM, a SPRAY or a FOAM at or above a certain pressure level are disclosed in the following U.S. patents:
______________________________________ U.S. Pat. Nos. Patentee ______________________________________ 4,046,292 Corsette 4,191,313 Blake et al. 4,225,060 Kutik et al. 4,260,079 Cary et al. 4,606,480 Rodriguez Gazulla 4,618,077 Corsette Re. 33,235 Corsette 4,669,664 Garneau 4,728,009 Schmidt ______________________________________
The non-analogous Corsette U.S. Pat. No. 4,046,292 discloses a dispensing pump in which an outlet valve will remain open only when the pumping pressure established by a pump piston is maintained above a predetermined minimum. A pump cylinder in which the pump piston reciprocates vertically comprises a unitary part of the outlet valve and also communicates freely with an expansible and contractible pressure accumulation chamber defined in part by the outlet valve and in part by the stationary pump housing. The pump piston depends from a vertically movable plunger into a cylinder formed in the outlet valve member. The piston and the outlet valve member are moved independently of each other while a stationary outlet for the finger actuated pump is placed in communication with the pressure accumulation chamber which includes the cylinder only when the pressure within that chamber is at or above the predetermined minimum pressure.
The Blake et al. U.S. Pat. No. 4,191,313 also utilizes an accumulation chamber and discloses a trigger operated dispenser comprising a plurality of chambers with movable members therein. An accumulating chamber is separated by a wall from a pump cylinder chamber in which is received a piston. A tapered opening is formed in this wall and a conically-shaped diaphragm-like end wall is integrally formed with a valving element that includes a conical tip which has a tapered end portion at the end of a valve pintle integral with the diaphragm-like end wall. During a pumping stroke of the piston, when it is moved inwardly into the cylinder, pressure builds up in the pumping cylinder until it overcomes the force of the diaphragm-like end wall and forces the tapered end portion or popper type valve away from the tapered opening to open the valve to allow pressurized liquid to enter the accumulation chamber. The liquid that flows through the valve port into the accumulation chamber acts against a free floating piston therein which then moves rearwardly against the bias of a spring element to accumulate an amount of material therein under pressure. Simultaneously, the pressured material flows through a port to a nozzle of the sprayer for discharge.
The non-analogous Kutik et al. U.S. Pat. No. 4,225,060 discloses a continuous pumping system in which a storage compartment formed in the upper end of a hollow piston by a spring loaded accumulation piston and cylinder assembly in the hollow piston in a vertical pumping assembly includes an accumulator spring which stays at a relatively constant length when pumping product to keep a relatively constant pressure on the product to maintain a steady stream of product emerging from the pumping system. Here, a pivotable lever arm is moved inwardly against an annular flange on the hollow piston which has a spring acting between a stationary container cap and the annular flange. As this hollow stem or piston moves downwardly, liquid is forced upwardly into the hollow piston. At the same time, the accumulator piston and accumulator spring that are received in the upper portion of the hollow piston maintain pressure on the liquid now permitted to escape through an outlet orifice connected to an upper portion of the hollow piston.
The Rodriguez Gazulla U.S. Pat. No. 4,606,480 discloses a trigger sprayer wherein a pumping mechanism is moved vertically upwardly when the trigger is depressed to compress liquid in a pump chamber which has a side port opening which is closed by a tapered end of a stem (poppet type valve) in an outlet waterway or conduit which has a spring therein acting against the stem to force the tapered end thereof against a tapered end of the opening. Thus, liquid cannot escape from the pumping chamber until a predetermined pressure is reached for moving the popper type valve at the end of the stem against a spring. The stem fills up a substantial volume of the conduit thereby minimizing the volume through which the pressure liquid must travel to reach an outlet nozzle of the sprayer.
In Cary et al., U.S. Pat. No. 4,260,079 there is disclosed a manually operated dispensing device which includes a bellows, a valve which is located at the inner end of the bellows in each of three embodiments, which is formed by a flexible wall of the bellows at an inner end thereof and which, as the bellows is compressed upon the squeezing of a trigger to create a higher pressure of liquid in the bellows, is caused to deflect or open to allow liquid to pass by the valve into a discharge conduit leading to an outlet orifice in a nozzle cap.
The Corsette U.S. Pat. No. 4,618,077 and the Corsette Reissue Patent U.S. Pat. No. Re. 33,235 disclose a trigger sprayer that includes a thimble-shaped valving element containing inlet and outlet valves and located within a cylindrical portion of a body of the sprayer. A pressure accumulation chamber is defined between the pump body and the valving element at the rear end of the cylinder. A pump piston is received in the thimble-shaped valving element and on an inward stroke thereof compresses liquid within the valving element until liquid entering into an area between the valving element and a back surface of the open cylindrical portion of the pump body builds up enough force to force the valving element acting against a spring positioned between the outer end of the valving element and the outer end of the piston, forward to allow liquid to pass behind the valving element to an outlet waterway.
The Garneau U.S. Pat. No. 4,669,664 teaches a conically shaped skirt valve member that includes a conical skirt on an elongate stem such that the stem reduces part of the volume through which the liquid being ejected must pass to reach an outlet orifice in an outlet nozzle.
The Schmidt U.S. Pat. No. 4,728,009 discloses a trigger sprayer having in an outlet waterway thereof an elongate member which reduces the volume of the outlet waterway passage through which liquid being pumped must pass before engaging a conical skirt-like umbrella valve which is deflected to allow pressurized liquid to pass therearound to reach an outlet orifice.